Cracking system and process integrating hydrocracking and fluidized catalytic cracking

ABSTRACT

A system and method of cracking hydrocarbon feedstocks is provided that allows for significant flexibility in terms of the desired product yield. An integrated process includes introducing the feedstock and hydrogen into a first hydrocracking reaction zone containing a first hydrocracking catalyst to produce a first zone effluent. The first zone effluent and optionally additional hydrogen are passed to a second hydrocracking reaction zone containing a second hydrocracking catalyst to produce a second zone effluent. The second zone effluent is conveyed to a fractionating zone to at least a low boiling fraction and a high boiling fraction, and optionally one or more intermediate fractions. The bottoms fraction is passed to a fluidized catalytic cracking reaction and separation zone, from which olefins and gasoline are recovered. At least a portion of remaining cycle oil is passed from the fluidized catalytic cracking reaction and separation zone to the first and/or second hydrocracking reaction zone.

RELATED APPLICATIONS

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to integrated cracking systems andprocesses that combine hydrocracking and fluidized catalytic crackingoperations, in particular for enhanced flexibility in the production oflight olefinic and middle distillate products.

2. Description of Related Art

Hydrocracking processes are used commercially in a large number ofpetroleum refineries. They are used to process a variety of feedsboiling in the range of 370° C. to 520° C. in conventional hydrocrackingunits and boiling at 520° C. and above in the residue hydrocrackingunits. In general, hydrocracking processes split the molecules of thefeed into smaller, i.e., lighter, molecules having higher averagevolatility and economic value. Additionally, hydrocracking processestypically improve the quality of the hydrocarbon feedstock by increasingthe hydrogen to carbon ratio and by removing organosulfur andorganonitrogen compounds. The significant economic benefit derived fromhydrocracking operations has resulted in substantial development ofprocess improvements and more active catalysts.

Mild hydrocracking or single stage once-through hydrocracking occurs atoperating conditions that are more severe than hydrotreating processes,and less severe than conventional full pressure hydrocracking processes.This hydrocracking process is more cost effective, but typically resultsin lower product yields and quality. The mild hydrocracking processproduces less mid-distillate products of a relatively lower quality ascompared to conventional hydrocracking. Single or multiple catalystssystems can be used depending upon the feedstock processed and productspecifications. Single stage hydrocracking is the simplest of thevarious configurations, and is typically designed to maximizemid-distillate yield over a single or dual catalyst systems. Dualcatalyst systems can be deployed as a stacked-bed configuration or inmultiple reactors.

In a series-flow configuration the entire hydrotreated/hydrocrackedproduct stream from the first reactor, including light gases (e.g.,C₁-C₄, H₂S, NH₃) and all remaining hydrocarbons, are sent to the secondreactor. In two-stage configurations the feedstock is refined by passingit over a hydrotreating catalyst bed in the first reactor. The effluentsare passed to a fractionator column to separate the light gases, naphthaand diesel products boiling in the temperature range of 36° C. to 370°C. The hydrocarbons boiling above 370° C. are then passed to the secondreactor for additional cracking.

In fluidized catalytic cracking (FCC) processes, petroleum derivedhydrocarbons are catalytically cracked with an acidic catalystmaintained in a fluidized state, which is regenerated on a continuousbasis. The main product from such processes has generally been gasoline.Other products are also produced in smaller quantities via FCC processessuch as liquid petroleum gas and cracked gas oil. Coke deposited on thecatalyst is burned off at high temperatures and in the presence of airprior to recycling regenerated catalyst back to the reaction zone.

In recent years there has been a tendency to produce, in addition togasoline, light olefins by FCC operations, which are valuable rawmaterials for various chemical processes. These operations havesignificant economic advantages, particularly with respect to oilrefineries that are highly integrated with petrochemical productionfacilities.

There are different methods to produce light olefins by FCC operations.Certain FCC operations are based on a short contact time of thefeedstock with the catalyst, e.g., as disclosed in U.S. Pat. Nos.4,419,221, 3,074,878, and 5,462,652, which are incorporated by referenceherein. However, the short contact time between feedstock and catalysttypically results in relatively low feed conversion.

Other FCC operations are based on using pentasil-type zeolite, forinstance, as disclosed in U.S. Pat. No. 5,326,465, which is incorporatedby reference herein. However, the use of a pentasil-type zeolitecatalyst will only enhance the yield of light fraction hydrocarbons byexcessive cracking of the gasoline fraction, which is also a high valueproduct.

Additional FCC processes are based on carrying out the crackingreactions at high temperature, such as that disclosed in U.S. Pat. No.4,980,053, which is incorporated by reference herein. However, thismethod can result in relatively high levels of dry gases production.

Further FCC operations are based on cracking the feed oil at hightemperature and short contact time and using a catalyst mixture ofspecific base cracking catalyst and an additive containing ashape-selective zeolite, as disclosed in U.S. Pat. No. 6,656,346, whichis incorporated by reference herein. Processes based on this method arealso known as High Severity Fluidized Catalytic Cracking (HS-FCC).Features of this process include a downflow reactor, high reactiontemperature, short contact time, and high catalyst to oil ratio.

Downflow reactors permit higher catalyst to oil ratio, since lifting ofsolid catalyst particles by vaporized feed is not required, and this isparticularly suitable for HS-FCC. In addition, HS-FCC processes areoperated under considerably higher reaction temperatures (550° C. to650° C.) as compared to conventional FCC processes. Under these reactiontemperatures, two competing cracking reactions occur, thermal crackingand catalytic cracking. Thermal cracking contributes to the formation oflighter products, such as dry gas and coke, whereas catalytic crackingincreases propylene and butylene yield. The short residence time in thedownflow reactor is also favorable to minimize thermal cracking.Undesirable secondary reactions such as hydrogen-transfer reactions,which consume olefins, are suppressed. The desired short residence timeis attained by mixing and dispersing catalyst particles and feed at thereactor inlet followed by immediate separation at the reactor outlet. Inorder to compensate for the decrease in conversion due to the shortcontact time, the HS-FCC process is operated at relatively highcatalysts to oil ratio.

While individual and discrete hydrocracking and FCC processes are welldeveloped and suitable for their intended purposes, there nonethelessremains a need for increased flexibility, efficiency and high-valueproduct yield in refinery operations.

SUMMARY OF THE INVENTION

In accordance with one or more embodiments, the invention relates to asystem and method of cracking hydrocarbon feedstocks in a manner thatallows for significant flexibility in terms of the desired productyield.

In accordance with one or more embodiments, an integrated process forconversion of a feedstock is provided, in particular for feedstockscontaining hydrocarbons having a boiling point greater than 300° C. Theintegrated process, including hydrocracking and fluidized catalyticcracking, includes the steps of:

a. introducing the feedstock and hydrogen into a first hydrocrackingreaction zone containing a first hydrocracking catalyst to produce afirst zone effluent;

b. passing the first zone effluent and optionally additional hydrogen toa second hydrocracking reaction zone containing a second hydrocrackingcatalyst to produce a second zone effluent;

c. passing the second zone effluent to a fractionating zone to at leasta low boiling fraction and a high boiling fraction, and optionally oneor more intermediate fractions;

d. passing the bottoms fraction to a fluidized catalytic crackingreaction and separation zone operating under conditions that promoteformation of olefins and gasoline and that minimize olefin-consumingreactions;

e. recovering olefins from the fluidized catalytic cracking reaction andseparation zone;

f. recovering gasoline from the fluidized catalytic cracking reactionand separation zone;

g. conveying at least a portion of remaining cycle oil from thefluidized catalytic cracking reaction and separation zone to the firstand/or second hydrocracking reaction zone.

Still other aspects, embodiments, and advantages of these exemplaryaspects and embodiments, are discussed in detail below. Moreover, it isto be understood that both the foregoing information and the followingdetailed description are merely illustrative examples of various aspectsand embodiments, and are intended to provide an overview or frameworkfor understanding the nature and character of the claimed aspects andembodiments. The accompanying drawings are included to provideillustration and a further understanding of the various aspects andembodiments, and are incorporated in and constitute a part of thisspecification. The drawings, together with the remainder of thespecification, serve to explain principles and operations of thedescribed and claimed aspects and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail below and withreference to the attached drawings all of which describe or relate toapparatus, systems and methods of the present invention. For the purposeof illustrating the invention, there are shown in the drawingsembodiments which are presently preferred, with optional unitoperations, inlets, outlets and/or streams shown in dashed lines. In thefigures, which are not intended to be drawn to scale, each similarcomponent that is illustrated in various figures is represented by alike numeral. In the figures:

FIG. 1 is a process flow diagram of an integrated hydrocracking andfluidized catalytic cracking system described herein;

FIG. 2 is a generalized diagram of a downflow fluidized catalyticcracking reactor system; and

FIG. 3 is a generalized diagram of a riser fluidized catalytic crackingreactor system.

DETAILED DESCRIPTION OF THE INVENTION

Integrated processes and apparatus are provided for the refining andhydrocracking hydrocarbon feeds, such as vacuum gas oil, to obtainimproved yields and higher quality products, including light olefinspropylene and butylenes, and middle distillate products. Typically, ahydrocracking unit does not produce light olefins, and conventional orhigh severity FCC processes do not produce mid distillates suitable foruse as transportation fuel. However, the integrated processes andapparatus provided herein produces both light olefins and middledistillate products while minimizing production of side products, as allor most unconverted bottoms are processed within the battery limits ofthe integrated unit. According to the present processes and apparatus,the FCC process bottoms (e.g., boiling at 370° C. and above) arerecycled to the first and/or second stage of the hydrocracking reactionzone for hydrogenation and further cracking, which improves the overallyield of middle distillates, i.e., from both the FCC reaction andseparation zone, and from the hydrocracking product fractionator.

Importantly, by integrating hydrocracking and FCC operations, a level offlexibility is attained that is not possible by the individual,non-integrated processes. For instance, in operations in which thehydrocracking unit conversion is relatively high, e.g., 80 V %, due tofactors including but not limited to reactor selection, catalyst type,extent of catalytic activity reduction, operating conditions and theparticular characteristics of the feedstock, there will be lessfeedstock to the FCC unit and as a result the integrated unit willproduce more naphtha and diesel product and less light olefins such aspropylene. On the other hand, in operations in which the hydrocrackingunit conversion is relatively low level, e.g., 60 V %, there will be arelative increase in feedstock to the FCC unit thereby resulting in arelatively higher level of olefinic product. Table 1 shows exemplaryvolume percentage yields for olefin, naphtha and middle distillateproducts relative to the conversion level in the hydrocracking unit.Notably, the olefin yield can range from as high as about 19 V % whenthe hydrocracker conversion is only 20 V % to 0 V % when thehydrocracker conversion is 100 V %, wherein the volume percentages arebased on the volume of initial feed.

TABLE 1 Hydrocracker Olefin Naphtha Middle Distillate Conversion FCCFeed* Yield Yield Yield 20 80 19.2 7.17 12.06 30 70 16.8 10.76 18.09 4060 14.4 14.34 24.11 50 50 12 17.93 30.14 60 40 9.6 21.51 36.17 70 30 7.225.10 42.20 80 20 4.8 28.69 48.23 90 10 2.4 32.27 54.26 100 0 0 35.8660.29 *The FCC feed values are approximate and based on thehydrocracking conversion level. The values may be slightly higher orlower due to the composition of gas feed and quantities of hydrogenincorporated in the hydrocracker.

In general, the process and apparatus for improved cracking include afirst hydrocracking reaction zone in which the feedstock is hydrotreated(i.e., hydrodesulfurized, hydrodenitrognized, hydrogenated) and crackedin the presence of hydrogen. Effluents from the first hydrocrackingreaction zone, containing cracked hydrocarbons yielded from the firsthydrocracking reaction zone, partially cracked hydrocarbons andunconverted hydrocarbons, and optionally additional hydrogen, are passedto a second hydrocracking reaction zone. Effluents from the secondhydrocracking reaction zone are fractionated to produce at least a lowboiling fraction and a high boiling (bottoms) fraction, and optionallyone or more intermediate fractions. Fractionator bottoms includingunconverted hydrocarbons and any cracked hydrocarbons and/or partiallycracked hydrocarbons boiling above a predetermined fluidized catalyticcracking feed cut point are passed to a fluidized catalytic cracking(FCC) reaction and separation zone. The FCC charge is cracked, and theFCC effluent is separated in into light olefins and gasoline that resultfrom the cracking reactions, and heavier components includingunconverted hydrocarbons and partially cracked hydrocarbons, e.g., cycleoils. The heavier components are further hydrogenated and cracked in thefirst and/or second hydrocracking reaction zone.

In particular, and referring to FIG. 1, a process flow diagram of anintegrated hydrocracking and FCC apparatus 52 is provided. Apparatus 52includes a first hydrocracking reaction zone 58 containing a firsthydrocracking catalyst, a second hydrocracking reaction zone 64containing a second hydrocracking catalyst, a fractionating zone 70 andan FCC reaction and separation zone 82.

First hydrocracking reaction zone 58 includes a feed inlet 57 forreceiving feedstock and hydrogen gas. Inlet 57 is in fluid communicationwith a source of feedstock via a conduit 54 and a source of hydrogen viaa conduit 56. In additional embodiments a first hydrocracking reactionzone can include a separate feedstock inlet and one or more separatehydrogen inlets.

In the first hydrocracking reaction zone 58, an intermediate product isproduced including gases, naphtha, middle distillates and higher boilinghydrocarbons, including partially cracked hydrocarbons and unconvertedhydrocarbons. The intermediate product is discharged via a firsthydrocracking reaction zone outlet 60 and is conveyed to secondhydrocracking reaction zone 64.

Second hydrocracking reaction zone 64 includes an inlet 63 for receivingthe intermediate product and optionally additional hydrogen. Inlet 63 isin fluid communication with the first hydrocracking reaction zone outlet60 and an optional source of hydrogen via a conduit 62. In additionalembodiments the second hydrocracking reaction zone can include separateintermediate product inlet and one or more separate hydrogen inlets.Note that the source of hydrogen can be the same source as that feedsfirst hydrocracking reaction zone 58, or a separate source. Forinstance, in certain systems, it can be desirable to provide hydrogen ofdifferent purity levels and/or hydrogen partial pressure to firsthydrocracking reaction zone 58 and second hydrocracking reaction zone64.

Effluent discharged from second hydrocracking reaction zone 64 via anoutlet 68 includes gases, naphtha, middle distillates and higher boilinghydrocarbons, including partially cracked and unconverted hydrocarbons,which is conveyed to an inlet 69 of fractionating zone 70.

In one embodiment, the charge is fractioned into overhead gas, e.g.,containing molecules having a boiling point below about 36° C., that isdischarged via an outlet 72; optionally one or more intermediatefractions including a naphtha fraction having a boiling point in therange of about 36° C. to about 180° C. that is discharged via outlet 74and a middle distillate fraction having a boiling point in the range ofabout 180° C. to about 370° C. that is discharged via outlet 76; and abottoms fraction, e.g., having an initial boiling point of about 370°C., that is discharged via outlet 78. A portion 72 a of the overheadgases, after separation and cleaning, can be recycled to firsthydrocracking reaction zone 58 and/or second hydrocracking reaction zone64.

In another embodiment, the charge is fractioned into a low boilingfraction that is discharged via outlet 72, an intermediate boilingfraction that is discharged via an outlet (which can be one of eitheroutlet 74 or outlet 76, whereby the other outlet is not required) and ahigh boiling fraction that is discharged via outlet 78. The intermediateboiling fraction can be passed to downstream unit operations (not shown)for further separation or processing, e.g., into a naphtha fraction anda middle distillate fraction.

In an additional embodiment, naphtha and/or middle distillates from thefractionating zone 70 can be passed to the FCC reaction and separationzone 82 (not shown in FIG. 1), for instance, for conversion into lightolefins and/or gasoline. The naphtha and/or middle distillates can beconveyed along with the high boiling fraction. Alternatively, naphthaand/or middle distillates can be conveyed separately from the highboiling fraction to different risers or downers in the FCC unit, or toseparate FCC units.

In a further embodiment, the charge is fractioned into a low boilingfraction that is discharged via outlet 72 and a high boiling fractionthat is discharged via outlet 78 (whereby outlets 74 and 76 are notrequired). The cut point for the fractionator in this embodiment can be,for instance, 370° C., in which a naphtha fraction boiling in the rangeof about 36° C. to about 180° C. and a middle distillate fractionboiling in the range of about 180° C. to about 370° C. are dischargedalong with overhead gases, and passed to downstream unit operations (notshown) for further separation or processing, including collection ofnaphtha and middle distillate. A portion 72 a of the overhead gases,including hydrogen and light hydrocarbons such as C₁ to C₄, can berecycled to first hydrocracking reaction zone 58 and/or secondhydrocracking reaction zone 64 after separation and cleaning. Further,the cut point for the fractionator in this embodiment can be lower than370° C., whereby the high boiling fraction contains hydrocarbons boilingin the middle distillate and possibly in the naphtha range that aredischarged via outlet 78.

In certain embodiments, an optional bleed outlet 79 is provided in fluidcommunication with the discharge stream from outlet 78 to remove heavypoly nuclear aromatic compounds, which could cause equipment fouling.The portion of the bottoms or high boiling fraction that is bled can beabout 0 V % to about 10 V %, in certain embodiments about 1 V % to about5 V % and in further embodiments about 1 V % to about 3 V %.

The bottoms fraction or high boiling fraction that is discharged viaoutlet 78 is conveyed to FCC reaction and separation zone 82 thatoperates under conditions that promote formation of olefins whileminimizing olefin-consuming reactions, such as hydrogen-transferreactions. FCC reaction and separation zone 82 generally includes one ormore reaction sections in which the charge and an effective quantity offluidized cracking catalyst are introduced. In addition, FCC reactionand separation zone 82 includes a regeneration section in which crackingcatalysts that have become coked, and hence access to the activecatalytic sites becomes limited or nonexistent, are subjected to hightemperatures and a source of oxygen to combust the accumulated coke andsteam to strip heavy oil adsorbed on the spent catalyst. Furthermore,FCC reaction and separation zone 82 includes a separation apparatus,such as a fractionating tower, to partition the FCC reaction productsinto olefins, gasoline and heavy products. While arrangements of certainFCC units are described herein with respect to FIGS. 2 and 3, one ofordinary skill in the art will appreciate that other well-known FCCunits can be employed.

In general, FCC reaction and separation zone 82 includes a feed inlet 98in fluid communication with the high boiling or bottoms outlet 78 of thefractionating zone 70. In additional embodiments, a source of feedstockthat is separate from the feedstock introduced to first hydrocrackingreaction zone 58 is optionally conveyed into FCC reaction and separationzone 82, e.g., via a conduit 97. This feedstock can be the same ordifferent in its characteristics than the feedstock to introduced tofirst hydrocracking reaction zone 58. In certain embodiments, thefeedstock introduced via conduit 97 is treated vacuum gas oil having lowsulfur and nitrogen content. In addition, steam can be integrated withthe feed 98 to atomize or disperse the feed into the FCC unit.

FCC reaction and separation zone 82 includes plural outlets fordischarging products, partially cracked hydrocarbons, unreactedhydrocarbons and by-products. In particular, effluent from the FCCreactor is fractioned and discharged via a water and gas outlet 84, anolefin outlet 86, a gasoline outlet 88, a light cycle oil outlet 90 anda heavy cycle oil outlet 91. In certain embodiments, both light andheavy cycle oil can be discharged via a single outlet. Olefins andgasoline are recovered and collected as final or intermediate products,i.e., that can be subjected to further downstream separation and/orprocessing.

Cycle oil, including light cycle oil from FCC reaction and separationzone outlet 90 and heavy cycle oil from FCC reaction and separation zoneoutlet 91, are combined and passed, e.g., via a conduit 94, to secondhydrocracking reaction zone 64. A bleed stream 92, which is a slurry oilstream that is heavier than the heavy cycle oil stream and typicallycontains catalyst particles, can also be discharged from the FCCreaction and separation zone 82. In certain optional embodiments, atleast a portion of the cycle oil from FCC reaction and separation zone82 can be recycled, e.g., via a conduit 96, and combined with thefeedstock at conduit 54 and introduced to first hydrocracking reactionzone 58.

Advantageously, in the process of the present invention, middledistillate production can be about 10 V % to about 60 V %, in certainembodiments about 20 V % to about 50 V %, and in further embodimentsabout 30 V % to about 40 V %, based on the initial feed via inlets 57and 97. In addition, light olefin production can be about 3 V % to about20 V %, in certain embodiments about 5 V % to about 20 V %, and infurther embodiments about 10 V % to about 20 V %, based on the initialfeed via inlets 57 and 97.

The initial feedstock for use in above-described apparatus and process(i.e., introduced via conduit 54 and optionally via conduit 97) can be apartially refined oil product obtained from various sources. In general,the feedstock contains hydrocarbons having boiling point greater thanabout 300° C., and in certain embodiments in vacuum gas oil range ofabout 370° C. to about 600° C. The source of the partially refined oilfeedstock can be crude oil, synthetic crude oil, bitumen, oil sand,shell oil, coal liquids, or a combination including one of the foregoingsources. For example, the partially refined oil feedstock can be vacuumgas oil, deasphalted oil and/or demetallized oil obtained from a solventdeasphalting process, light coker or heavy coker gas oil obtained from acoker process, cycle oil obtained from FCC process separate from theintegrated FCC process described herein, gas oil obtained from avisbreaking process, or any combination of the foregoing partiallyrefined oil products. In certain embodiments, vacuum gas oil is asuitable initial feedstock for the integrated cracking process.

The first hydrocracking reaction zone and the second hydrocrackingreaction zone can include the same type of reactor or different types ofreactors. Suitable reaction apparatus include fixed bed reactors movingbed reactor, ebullated bed reactors, baffle-equipped slurry bathreactors, stirring bath reactors, rotary tube reactors, slurry bedreactors, or other suitable reaction apparatus as will be appreciated byone of ordinary skill in the art. In certain embodiments, and inparticular for vacuum gas oil and similar feedstocks, fixed bed reactorsare utilized for both the first and second hydrocracking reaction zones.In additional embodiments, and in particular for heavier feedstocks andother difficult to crack feedstocks, ebullated bed reactors are utilizedfor both the first and second hydrocracking reaction zones.

In general, the operating conditions for the reactor in a hydrocrackingreaction zone include:

reaction temperature of about 300° C. to about 500° C., in certainembodiments about 330° C. to about 475° C., and in further embodimentsabout 330° C. to about 450° C.;

hydrogen partial pressure of about 60 Kg/cm² to about 300 Kg/cm², incertain embodiments about 100 Kg/cm² to about 200 Kg/cm², and in furtherembodiments about 130 Kg/cm² to about 180 Kg/cm²;

liquid hourly space velocity (LHSV) of about 0.1 h⁻¹ to about 10 h⁻¹, incertain embodiments about 0.25 h⁻¹ to about 5 h⁻¹, and in furtherembodiments of 0.5 h⁻¹ to 2 h⁻¹; and

hydrogen/oil ratio of about 500 normalized m³ per m³ (Nm³/m³) to about2500 Nm³/m³, in certain embodiments about 800 Nm³/m³ to about 2000Nm³/m³, and in further embodiments about 1000 Nm³/m³ to about 1500Nm³/m³.

A catalyst that is suitable for the particular charge and the desiredproduct is maintained in the hydrocracking reactors within the zones. Asis known to those having ordinary skill in the art, the catalyst can bedifferent in the first and second zones.

In certain embodiments, the first zone hydrocracking catalyst includesany one of or combination including amorphous alumina catalysts,amorphous silica alumina catalysts, zeolite based catalyst. The firstzone hydrocracking catalyst can possess an active phase materialincluding, in certain embodiments, any one of or combination includingNi, W, Mo, or Co.

In certain embodiments in which an objective in the first hydrocrackingreaction zone is hydrodenitrogenation, acidic alumina or silica aluminabased catalysts loaded with Ni—Mo or Ni—W active metals, or combinationsthereof, are used. Hydrodenitrogenation reactions are commonly targetedin the first hydrocracking reaction zone as second hydrocrackingreaction zone catalysts can be provided that commonly not tolerant tothe presence of nitrogen. Hydrodesulfurization reactions also occur atthe process pressures and temperatures using these hydrodenitrogenationcatalysts. A substantial amount of sulfur compounds are converted at thehydrodenitrogenation conditions. In embodiments in which the objectiveis to remove all nitrogen and to increase the conversion ofhydrocarbons, silica alumina, zeolite or combination thereof are used ascatalysts, with active metals including Ni—Mo, Ni—W or combinationsthereof.

In certain embodiments, the second zone hydrocracking catalyst includesany one of or combination including zeolite based catalysts, amorphousalumina catalysts, amorphous silica alumina catalysts. In order toeffectively convert refined and partially cracked feedstocks intolighter fractions, suitable catalysts include acidic catalysts such assilica alumina, zeolite or combinations thereof, with active metalsincluding Ni—Mo, Ni—W or combinations thereof.

Catalytic cracking reactions occur in FCC reaction and separation zone82 under conditions that promote formation of olefins and that minimizeolefin-consuming reactions, such as hydrogen-transfer reactions. Theseconditions generally depend on the type and configuration of the FCCunit.

Various types of FCC reactors operate under conditions that promoteformation of olefins and gasoline are known, including the High-SeverityFCC process developed by Nippon Oil Corporation of Japan, Deep CatalyticCracking (DCC-I and DCC-II) and Catalytic Pyrolysis Process developed bySINOPEC Research Institute of Petroleum Processing of Beijing, China,the Indmax process developed by Indian Oil Corporation of India,MAXOFIN™ developed by ExxonMobil of Irving, Tex., USA and KBR, Inc. ofHouston, Tex., USA, NExCC™ developed by Fortum Corporation of Fortum,Finland, PetroFCC developed by UOP LLC of Des Plaines, Ill., USA,Selective Component Cracking developed by ABB Lummus Global, Inc. ofBloomfield, N.J., USA, High-Olefins FCC developed by Petrobras ofBrazil, and Ultra Selective Cracking developed by Stone & Webster,Incorporated of Stoughton, Mass., USA.

In certain embodiments, a suitable high severity FCC unit operationincludes a downflow reactor and is characterized by high reactiontemperature, short contact time and high catalyst to oil ratio. Adownflow reactor permits higher catalyst to oil ratio because therequirement to lift the catalyst by vaporized feed is not required.Reaction temperatures are in the range of about 550° C. to about 650°C., which is higher than conventional FCC reaction temperatures. Underthese reaction temperatures, two competing cracking reactions, thermalcracking and catalytic cracking, occur. Thermal cracking contributes tothe formation of lighter products, mainly dry gas and coke, whilecatalytic cracking increases propylene yield. Therefore, the residencetime in the downflow reactor is relatively short, e.g., less than about1 second, and in certain embodiments about 0.2-0.7 seconds, to minimizethermal cracking. Undesirable secondary reactions such ashydrogen-transfer reactions, which consume olefins, are suppressed dueto the very short residence times. To maximize conversion during theshort residence time, a high catalyst to oil ratio is used, e.g.,greater than 20:1, and catalysts and the feedstock are admixed anddispersed at the reactor inlet and separated immediately at the reactoroutlet.

In certain embodiments, an FCC unit configured with a downflow reactoris provided that operates under conditions that promote formation ofolefins and that minimize olefin-consuming reactions, such ashydrogen-transfer reactions. FIG. 2 is a generalized process flowdiagram of an FCC unit 100 which includes a downflow reactor and can beused in the hybrid system and process according to the presentinvention. FCC unit 100 includes a reactor/separator 110 having areaction zone 114 and a separation zone 116. FCC unit 100 also includesa regeneration zone 118 for regenerating spent catalyst.

In particular, a charge 120 is introduced to the reaction zone, incertain embodiments also accompanied by steam or other suitable gas foratomization of the feed, and with an effective quantity of heated freshor hot regenerated solid cracking catalyst particles from regenerationzone 118 is also transferred, e.g., through a downwardly directedconduit or pipe 122, commonly referred to as a transfer line orstandpipe, to a withdrawal well or hopper (not shown) at the top ofreaction zone 114. Hot catalyst flow is typically allowed to stabilizein order to be uniformly directed into the mix zone or feed injectionportion of reaction zone 114.

The bottoms fraction from the fractionating zone serves as the charge tothe FCC unit 100, alone or in combination with an additional feed asdiscussed above. The charge is injected into a mixing zone through feedinjection nozzles typically situated proximate to the point ofintroduction of the regenerated catalyst into reaction zone 114. Thesemultiple injection nozzles result in the catalyst and oil mixingthoroughly and uniformly. Once the charge contacts the hot catalyst,cracking reactions occur. The reaction vapor of hydrocarbon crackedproducts, unreacted feed and catalyst mixture quickly flows through theremainder of reaction zone 114 and into a rapid separation zone 116 atthe bottom portion of reactor/separator 110. Cracked and uncrackedhydrocarbons are directed through a conduit or pipe 124 to aconventional product recovery section known in the art.

If necessary for temperature control, a quench injection can be providednear the bottom of reaction zone 114 immediately before the separationzone 116. This quench injection quickly reduces or stops the crackingreactions and can be utilized for controlling cracking severity andallows for added process flexibility.

The reaction temperature, i.e., the outlet temperature of the downflowreactor, can be controlled by opening and closing a catalyst slide valve(not shown) that controls the flow of regenerated catalyst fromregeneration zone 118 into the top of reaction zone 114. The heatrequired for the endothermic cracking reaction is supplied by theregenerated catalyst. By changing the flow rate of the hot regeneratedcatalyst, the operating severity or cracking conditions can becontrolled to produce the desired yields of light olefinic hydrocarbonsand gasoline.

A stripper 132 is also provided for separating oil from the catalyst,which is transferred to regeneration zone 118. The catalyst fromseparation zone 116 flows to the lower section of the stripper 132 thatincludes a catalyst stripping section into which a suitable strippinggas, such as steam, is introduced through streamline 134. The strippingsection is typically provided with several baffles or structured packing(not shown) over which the downwardly flowing catalyst passescounter—currently to the flowing stripping gas. The upwardly flowingstripping gas, which is typically steam, is used to “strip” or removeany additional hydrocarbons that remain in the catalyst pores or betweencatalyst particles.

The stripped or spent catalyst is transported by lift forces from thecombustion air stream 128 through a lift riser of the regeneration zone118. This spent catalyst, which can also be contacted with additionalcombustion air, undergoes controlled combustion of any accumulated coke.Flue gases are removed from the regenerator via conduit 130. In theregenerator, the heat produced from the combustion of the by-productcoke is transferred to the catalyst raising the temperature required toprovide heat for the endothermic cracking reaction in the reaction zone114.

In one embodiment, a suitable FCC unit 100 that can be integrated intothe system of FIG. 1 that promotes formation of olefins and thatminimizes olefin-consuming reactions includes a high severity FCCreactor, can be similar to those described in U.S. Pat. No. 6,656,346,and US Patent Publication Number 2002/0195373, both of which areincorporated herein by reference. Important properties of downflowreactors include introduction of feed at the top of the reactor withdownward flow, shorter residence time as compared to riser reactors, andhigh catalyst to oil ratio, e.g., in the range of about 20:1 to about30:1.

In general, the operating conditions for the reactor of a suitabledownflow FCC unit include:

reaction temperature of about 550° C. to about 650° C., in certainembodiments about 580° C. to about 630° C., and in further embodimentsabout 590° C. to about 620° C.;

reaction pressure of about 1 Kg/cm² to about 20 Kg/cm², in certainembodiments of about 1 Kg/cm² to about 10 Kg/cm², in further embodimentsof about 1 Kg/cm² to about 3 Kg/cm²;

contact time (in the reactor) of about 0.1 seconds to about 30 seconds,in certain embodiments about 0.1 seconds to about 10 seconds, and infurther embodiments about 0.2 seconds to about 0.7 seconds; and

a catalyst to feed ratio of about 1:1 to about 40:1, in certainembodiments about 1:1 to about 30:1, and in further embodiments about10:1 to about 30:1.

In certain embodiments, an FCC unit configured with a riser reactor isprovided that operates under conditions that promote formation ofolefins and that minimizes olefin-consuming reactions, such ashydrogen-transfer reactions. FIG. 3 is a generalized process flowdiagram of an FCC unit 200 which includes a riser reactor and can beused in the hybrid system and process according to the presentinvention. FCC unit 200 includes a reactor/separator 210 having a riserportion 212, a reaction zone 214 and a separation zone 216. FCC unit 200also includes a regeneration vessel 218 for regenerating spent catalyst.

Hydrocarbon feedstock is conveyed via a conduit 220, and in certainembodiments also accompanied by steam or other suitable gas foratomization of the feed, for admixture and intimate contact with aneffective quantity of heated fresh or regenerated solid crackingcatalyst particles which are conveyed via a conduit 222 fromregeneration vessel 218. The feed mixture and the cracking catalyst arecontacted under conditions to form a suspension that is introduced intothe riser 212.

In a continuous process, the mixture of cracking catalyst andhydrocarbon feedstock proceed upward through the riser 212 into reactionzone 214. In riser 212 and reaction zone 214, the hot cracking catalystparticles catalytically crack relatively large hydrocarbon molecules bycarbon-carbon bond cleavage.

During the reaction, as is conventional in FCC operations, the crackingcatalysts become coked and hence access to the active catalytic sites islimited or nonexistent. Reaction products are separated from the cokedcatalyst using any suitable configuration known in FCC units, generallyreferred to as the separation zone 216 in FCC unit 200, for instance,located at the top of the reactor 210 above the reaction zone 214. Theseparation zone can include any suitable apparatus known to those ofordinary skill in the art such as, for example, cyclones. The reactionproduct is withdrawn through conduit 224.

Catalyst particles containing coke deposits from fluid cracking of thehydrocarbon feedstock pass from the separation zone 214 through aconduit 226 to regeneration zone 218. In regeneration zone 218, thecoked catalyst comes into contact with a stream of oxygen-containinggas, e.g., pure oxygen or air, which enters regeneration zone 218 via aconduit 228. The regeneration zone 218 is operated in a configurationand under conditions that are known in typical FCC operations. Forinstance, regeneration zone 218 can operate as a fluidized bed toproduce regeneration off-gas comprising combustion products which isdischarged through a conduit 230. The hot regenerated catalyst istransferred from regeneration zone 218 through conduit 222 to the bottomportion of the riser 212 for admixture with the hydrocarbon feedstockand noted above.

In one embodiment, a suitable FCC unit 200 that can be integrated intothe system of FIG. 1 that promotes formation of olefins and thatminimizes olefin-consuming reactions includes a high severity FCCreactor, can be similar to that described in U.S. Pat. Nos. 7,312,370,6,538,169, and 5,326,465.

In an alternative embodiment, liquid products from fractionating zone70, including the bottoms fraction, the middle distillate fraction andthe naphtha fraction, can be separately introduced into one or moreseparate riser reactors of an FCC unit having multiple risers. Forinstance, the bottoms fraction can be introduced via a main riser, and astream of naphtha and/or middle distillates can be introduced via asecondary riser. In this manner, olefin production can be maximizedwhile minimizing the formation methane and ethane, since differentoperating conditions can be employed in each riser.

In general, the operating conditions for the reactor of a suitable riserFCC unit include:

reaction temperature of about 480° C. to about 650° C., in certainembodiments about 500° C. to about 620° C., and in further embodimentsabout 500° C. to about 600° C.;

reaction pressure of about 1 Kg/cm² to about 20 Kg/cm², in certainembodiments of about 1 Kg/cm² to about 10 Kg/cm², in further embodimentsof about 1 Kg/cm² to about 3 Kg/cm²;

contact time (in the reactor) of about 0.7 seconds to about 10 seconds,in certain embodiments of about 1 seconds to about 5 seconds, in furtherembodiments of about 1 seconds to about 2 seconds; and

a catalyst to feed ratio of about 1:1 to about 15:1, in certainembodiments of about 1:1 to about 10:1, in further embodiments of about8:1 to about 20:1.

A catalyst that is suitable for the particular charge and the desiredproduct is conveyed to the FCC reactor within the FCC reaction andseparation zone. In certain embodiments, to promote formation of olefinsand minimize olefin-consuming reactions, such as hydrogen-transferreactions, an FCC catalyst mixture is used in the FCC reaction andseparation zone, including an FCC base catalyst and an FCC catalystadditive.

In particular, a matrix of a base cracking catalyst can include one ormore clays such as kaolin, montmorilonite, halloysite and bentonite,and/or one or more inorganic porous oxides such as alumina, silica,boria, chromia, magnesia, zirconia, titania and silica-alumina. The basecracking catalyst preferably has a bulk density of 0.5 g/ml to 1.0 g/ml,an average particle diameter of 50 microns to 90 microns, a surface areaof 50 m²/g to 350 m²/g and a pore volume of 0.05 ml/g to 0.5 ml/g.

A suitable catalyst mixture contains, in addition to a base crackingcatalyst, an additive containing a shape-selective zeolite. The shapeselective zeolite referred to herein means a zeolite whose pore diameteris smaller than that of Y-type zeolite, so that hydrocarbons with onlylimited shape can enter the zeolite through its pores. Suitableshape-selective zeolite components include ZSM-5 zeolite, zeolite omega,SAPO-5 zeolite, SAPO-11 zeolite, SAPO34 zeolite, and pentasil-typealuminosilicates. The content of the shape-selective zeolite in theadditive is generally in the range of 20 to 70 wt %, and preferably inthe range of 30 to 60 wt %.

The additive preferably has a bulk density of 0.5 g/ml to 1.0 g/ml, anaverage particle diameter of 50 microns to 90 microns, a surface area of10 m²/g to 200 m²/g and a pore volume of 0.01 ml/g to 0.3 ml/g.

A percentage of the base cracking catalyst in the catalyst mixture canbe in the range of 60 to 95 wt % and a percentage of the additive in thecatalyst mixture is in a range of 5 to 40 wt %. If the percentage of thebase cracking catalyst is lower than 60 wt % or the percentage ofadditive is higher than 40 wt %, high light-fraction olefin yield cannotbe obtained, because of low conversions of the feed oil. If thepercentage of the base cracking catalyst is higher than 95 wt %, or thepercentage of the additive is lower than 5 wt %, high light-fractionolefin yield cannot be obtained, while high conversion of the feed oilcan be achieved. For the purpose of this simplified schematicillustration and description, the numerous valves, temperature sensors,electronic controllers and the like that are customarily employed andwell known to those of ordinary skill in the art of fluid catalystcracking are not included. Accompanying components that are inconventional hydrocracking units such as, for example, bleed streams,spent catalyst discharge sub-systems, and catalyst replacementsub-systems are also not shown. Further, accompanying components thatare in conventional FCC systems such as, for example, air supplies,catalyst hoppers and flue gas handling are not shown.

In some embodiments, the apparatus and/or individual unit operations ofthe apparatus can include a controller to monitor and adjust the productslate as desired. A controller can direct any of the parameters withinthe apparatus depending upon the desired operating conditions, whichmay, for example, be based on customer demand and/or market value. Acontroller can adjust or regulate valves, feeders or pumps associatedwith one or more unit operations based upon one or more signalsgenerated by operator data input and/or automatically retrieved data.

In one embodiment, a controller can be in electronic communication with,and adjust, valves, feeders and/or pumps associated with the effluentfrom fractionator 70 to direct a quantity of one or more intermediatefractions (e.g., middle distillate via outlet 76 and/or naphtha viaoutlet 74) to the FCC reaction and separation unit, rather than passingthem on to respective product pools, if the desired product slateincludes an increase in olefin production at the sacrifice of these oneor more intermediate fractions.

In another embodiment, a controller can be in electronic communicationwith, and adjust, thermostats, pressure regulators, valves, feedersand/or pumps associated with the first hydrocracking reaction zone 58and/or the second hydrocracking reaction zone 64 to adjust the residencetime, hydrogen feed rate, operating temperature, operating pressure, orother variables to modify the hydrocracker conversion efficiency.

The system and controller of one or more embodiments of the integratedhydrocracking and FCC apparatus provide a versatile unit having multiplemodes of operation, which can respond to multiple inputs to increase theflexibility of the recovered product. The controller can be implementedusing one or more computer systems which can be, for example, ageneral-purpose computer. Alternatively, the computer system can includespecially-programmed, special-purpose hardware, for example, anapplication-specific integrated circuit (ASIC) or controllers intendedfor a particular unit operation within a refinery.

The computer system can include one or more processors typicallyconnected to one or more memory devices, which can comprise, forexample, any one or more of a disk drive memory, a flash memory device,a RAM memory device, or other device for storing data. The memory istypically used for storing programs and data during operation of thesystem. For example, the memory can be used for storing historical datarelating to the parameters over a period of time, as well as operatingdata. Software, including programming code that implements embodimentsof the invention, can be stored on a computer readable and/or writeablenonvolatile recording medium, and then typically copied into memorywherein it can then be executed by one or more processors. Suchprogramming code can be written in any of a plurality of programminglanguages or combinations thereof.

Components of the computer system can be coupled by one or moreinterconnection mechanisms, which can include one or more busses, e.g.,between components that are integrated within a same device, and/or anetwork, e.g., between components that reside on separate discretedevices. The interconnection mechanism typically enables communications,e.g., data, instructions, to be exchanged between components of thesystem.

The computer system can also include one or more input devices, forexample, a keyboard, mouse, trackball, microphone, touch screen, andother man-machine interface devices as well as one or more outputdevices, for example, a printing device, display screen, or speaker. Inaddition, the computer system can contain one or more interfaces thatcan connect the computer system to a communication network, in additionor as an alternative to the network that can be formed by one or more ofthe components of the system.

According to one or more embodiments of the integrated crackingapparatus, the one or more input devices can include sensors and/or flowmeters for measuring any one or more parameters of the apparatus and/orunit operations thereof. Alternatively, one or more of the sensors, flowmeters, pumps, or other components of the apparatus can be connected toa communication network that is operatively coupled to the computersystem. Any one or more of the above can be coupled to another computersystem or component to communicate with the computer system over one ormore communication networks. Such a configuration permits any sensor orsignal-generating device to be located at a significant distance fromthe computer system and/or allow any sensor to be located at asignificant distance from any subsystem and/or the controller, whilestill providing data therebetween. Such communication mechanisms can beaffected by utilizing any suitable technique including but not limitedto those utilizing wireless protocols.

Although the computer system is described by way of example as one typeof computer system upon which various aspects of the integrated crackingapparatus can be practiced, it should be appreciated that the inventionis not limited to being implemented in software, or on the computersystem as exemplarily shown. Indeed, rather than implemented on, forexample, a general purpose computer system, the controller, orcomponents or subsections thereof, can alternatively be implemented as adedicated system or as a dedicated programmable logic controller (PLC)or in a distributed control system. Further, it should be appreciatedthat one or more features or aspects of the integrated crackingapparatus can be implemented in software, hardware or firmware, or anycombination thereof. For example, one or more segments of an algorithmexecutable by a controller can be performed in separate computers, whichin turn, can be in communication through one or more networks.

In some embodiments, one or more sensors and/or flow meters can beincluded at locations throughout the integrated cracking apparatus,which are in communication with a manual operator or an automatedcontrol system to implement a suitable process modification in aprogrammable logic controlled integrated cracking apparatus. In oneembodiment, an integrated cracking apparatus described herein includes acontroller which can be any suitable programmed or dedicated computersystem, PLC, or distributed control system. The flow rates of certainproduct streams from the fractionator 70 and the FCC reaction andseparation zone 82 can be measured, and flow can be redirected asnecessary to meet the requisite product slate.

In certain embodiments, under control of an operator or a controller asdescribed herein, the integrated cracking apparatus can operate withreduced efficiency catalyst in the first or second hydrocrackingreaction zones 58, 64 to favor bottoms production. i.e., having a levelof activity that is conventionally considered unsuitable for use intheir respective operations. In this manner, the quantity of feed to theFCC reaction and separation zone 82 is increased, thereby resulting inan increase in its products olefins and/or gasoline via outlets 86and/or 88.

In further embodiments, under control of an operator or a controller asdescribed herein, either or both of the first and second hydrocrackingzones 58, 64 can operate with a level of hydrogen feed that isrelatively low, i.e., at a level that is conventionally consideredunsuitable for use in their respective operations. In this manner, theexpense of hydrogen is reduced, while the quantity of feed to the FCCreaction and separation zone 82 is increased, thereby resulting in anincrease in its products olefins and/or gasoline via outlets 86 and/or88.

Factors that can result in various adjustments or controls includecustomer demand of the various hydrocarbon products, market value of thevarious hydrocarbon products, feedstock properties such as API gravityor heteroatom content, and product quality (e.g, gasoline and middistillate indicative properties such as octane number for gasoline andcetane number for mid distillates).

Example

A feedstock containing demetallized oil and light and heavy vacuum gasoil fractions was hydrocracked in a series flow hydrocracking unit. Thefeedstock blend was characterized by a density of 889.5 Kg/L, 2.32 W %of sulfur, 886 ppmw of nitrogen, 12.1 W % of hydrogen and 1.2 W % ofMicro carbon residue. The initial boiling point was 216° C.; 5 W %, 337°C.; 10 W %, 371° C.; 30 W %, 432° C.; 50 W %, 469° C.; 70 W %, 510° C.,90 W %, 585° C.; 95 W %, 632° C.; and the final boiling point was 721°C. A silica-alumina based catalyst was used in the first hydrocrackingreaction zone. The operating conditions for the first stage were: 115bars of hydrogen partial pressure, a temperature of 385° C., a liquidhourly space velocity of 0.27 h⁻¹, and a hydrogen to oil ratio of1263:1. The operating conditions for the second stage were: 115 bars ofhydrogen partial pressure, a temperature of 370° C., a liquid hourlyspace velocity of 0.80 h⁻¹, and a hydrogen to oil ratio of 1263:1. Theoverall conversion for material boiling above 375° C. was 70 W %. A USYzeolite catalyst was used in the second hydrocracking reaction zone.

The hydrocracking reaction zone effluent stream was separated and theunconverted hydrocracker bottoms stream (30 W %) having an initialboiling point of 370° C. was then sent to a high severity FCC unit witha downer reactor. A base catalyst of H-USY type zeolite with low acidsite density (75 V %) and an additive, 10 W % commercial ZSM-5 (25 V %)was used in the high severity FCC unit. The base catalyst and additivewere deactivated with 100% steam at 810° C. for 6 hours beforeevaluation in a fluid-bed steamer. The catalyst to oil ratio (mass:mass)was 30:1. The downer temperature was 630° C. 95 W % of the hydrocrackerbottoms were converted in the high severity FCC unit.

The overall conversion was 100 V % and the yields are summarized inTable 2 below.

TABLE 2 Yield W % V % H₂S 2.6 NH₃ 0.1 CO + CO₂ 0.0 H₂, C₁, C₂ 2.2 C₂ 0.3C₂= 1.2 C₃-C₄ 2.1 C₃= 7.5 C₄ 1.7 C₄= 7.1 Naphtha 25.1 31.1 MiddleDistillate 42.2 45.9 Gasoline 9.5 9.9 Coke 0.2 Total Yield* 102.0 TotalLiquid Yield 76.8 86.9 *Note that the yield in excess of 100% is due tothe addition of hydrogen in the hydrocracking unit.

Light and heavy cycle oils, which is around 5% were recycled back to thehydrocracker to obtain full conversion. The process yielded 42.2 W % ofmid distillate and 7.5 W % of propylene, with no residue. The totalgasoline production is estimated to be 32.0 W %, which includes thegasoline produced high severity FCC unit and the naphtha produced fromthe hydrocracker after downstream reformer processing to increase theresearch octane number from a value of about 80 to about 95 for use asgasoline (which slightly decreases the overall yield as isconventionally known).

The method and system of the present invention have been described aboveand in the attached drawings; however, modifications will be apparent tothose of ordinary skill in the art and the scope of protection for theinvention is to be defined by the claims that follow.

We claim:
 1. An integrated hydrocracking and fluidized catalyticcracking process for conversion of a feedstock containing hydrocarbonshaving a boiling point greater than 300° C. into middle distillates andlight olefins, propylene and butylene, the process comprising: a.introducing the feedstock and hydrogen into a first hydrocrackingreaction zone containing a first hydrocracking catalyst to produce afirst zone effluent; b. passing the first zone effluent and optionallyadditional hydrogen to a second hydrocracking reaction zone containing asecond hydrocracking catalyst to produce a second zone effluent; c.passing the second zone effluent to a fractionating zone to produce atleast a low boiling fraction and a high boiling fraction, and optionallyone or more intermediate fractions; d. passing the high boiling fractionto a fluidized catalytic cracking reaction and separation zone, whereinthe fluidized catalytic cracking reaction and separation zone operatesunder conditions that minimize olefin-consuming reactions and includes afluidized catalytic cracking reactor that is in a downflow configurationand operates at a reaction temperature in the range of 580° C. to 630°C., a catalyst-to-oil ratio of 10:1 to 30:1, and with a contact timebetween catalyst particles and the bottoms fraction of about 0.1 secondsto about 1 second; e. recovering light olefins propylene and butylenefrom the fluidized catalytic cracking reaction and separation zone in aquantity of at least about 10 V % to about 20 V %, based on the volumeof the initial feedstock; f. recovering middle distillate product fromthe fluidized catalytic cracking reaction and separation zone; and g.conveying at least a portion of remaining cycle oil from the fluidizedcatalytic cracking reaction and separation zone to the first and/orsecond hydrocracking reaction zone wherein the integrated process isoperated to afford flexibility based on a desired product slate byvarying the hydrocracking unit conversion efficiency in either or bothof the first and second hydrocracking zones, wherein varying thehydrocracking unit conversion efficiency is by one or more of; operatingwith reduced efficiency catalyst in the first or second hydrocrackingreaction zones to favor bottoms production and increase the quantity offeed to the fluidized catalytic cracking reactor thereby resulting in anincrease in its products olefins and/or gasoline; or operating with alevel of hydrogen feed that is relatively low to reduce the expense ofhydrogen and increase the quantity of feed to the to the fluidizedcatalytic cracking reactor thereby resulting in an increase in itsproducts olefins and/or gasoline.
 2. This process of claim 1, whereinstep (g) comprises conveying a portion of the remaining cycle oil to thesecond hydrocracking reaction zone.
 3. This process of claim 1, whereinstep (g) comprises conveying a portion of the remaining cycle oil to thefirst hydrocracking reaction zone.
 4. This process of claim 1, furthercomprising discharging gases from the fluidized catalytic crackingreaction and separation zone.
 5. The process of claim 1, furthercomprising recovering naphtha from the fractionating zone.
 6. Theprocess of claim 1, further comprising recovering middle distillatesfrom the fractionating zone.
 7. The process of claim 1, wherein aportion of the bottoms fraction from the fractionating zone is removedfrom the process.
 8. The process of claim 7, wherein the portion that isremoved is about 1 V % to about 10 V % of the bottoms fraction.
 9. Theprocess of claim 1, wherein step (d) further includes introducing anadditional feedstock to fluidized catalytic cracking reaction andseparation zone.
 10. The process of claim 1, wherein step (d) comprisesconveying a fluidized cracking catalyst mixture including the fluidizedcracking catalyst as a fluidized cracking base catalyst, and a catalystadditive.
 11. The process of claim 10, wherein the fluidized crackingbase catalyst comprises about 60 wt % to about 95 wt % of the totalfluidized cracking catalyst mixture.
 12. The process of claim 10,wherein the fluid cracking base catalyst is selected from the groupconsisting of clays and inorganic porous oxides.
 13. The process ofclaim 12, wherein the fluid cracking base catalyst has a bulk density of0.5 g/ml to 1.0 g/ml, an average particle diameter of 50 microns to 90microns, a surface area of 50 m²/g to 350 and a pore volume of 0.05 ml/gto 0.5 ml/g.
 14. The process of claim 10, wherein the catalyst additiveincludes a shape-selective zeolite.
 15. The process of claim 14, whereinthe shape selective zeolite is characterized by an average pore diameterthat is less then the average pore diameter of Y-type zeolite.
 16. Theprocess of claim 14, wherein the shape selective zeolite is selectedfrom the group consisting of ZSM-5 zeolite, zeolite omega, SAPO-5zeolite, SAPO-11 zeolite, SAPO-34 zeolite, pentasil-typealuminosilicate, and combinations comprising at least one of theforegoing shape selective zeolite.
 17. The process of claim 14, whereinthe shape selective zeolite having a bulk density of 0.5 g/ml to 1.0g/ml, an average particle diameter of 50 microns to 90 microns, asurface area of 10 m²/g to 200 m²/g and a pore volume of 0.01 ml/g to0.3 ml/g.
 18. The process of claim 14, wherein the fluid crackingcatalyst mixture includes about 5 wt % to about 40 wt % of the catalystadditive.
 19. The process of claim 14, wherein the catalyst additivecomprises about 20 wt % to about 70 wt % shape-selective zeolite. 20.The process of claim 14, wherein the catalyst additive comprises about30 wt % to about 60 wt % shape-selective zeolite.
 21. An integratedhydrocracking and fluidized catalytic cracking process for conversion ofa feedstock containing hydrocarbons having a boiling point greater than300° C. into middle distillates and light olefins, propylene andbutylene, the process comprising: a. introducing the feedstock andhydrogen into a first hydrocracking reaction zone containing a firsthydrocracking catalyst to produce a first zone effluent; b. passing thefirst zone effluent and optionally additional hydrogen to a secondhydrocracking reaction zone containing a second hydrocracking catalystto produce a second zone effluent; c. passing the second zone effluentto a fractionating zone to produce at least a low boiling fraction and ahigh boiling fraction, and optionally one or more intermediatefractions; d. passing the high boiling fraction to a fluidized catalyticcracking reaction and separation zone, wherein the fluidized catalyticcracking reaction and separation zone operates under conditions thatminimize olefin-consuming reactions and includes a fluidized catalyticcracking reactor that is in a riser configuration and operates at areaction temperature in the range of 500° C. to 620° C., acatalyst-to-oil ratio of 8:1 to 20:1, and with a contact time betweencatalyst particles and the bottoms fraction of about 1 second to about 2seconds; e. recovering light olefins propylene and butylene from thefluidized catalytic cracking reaction and separation zone in a quantityof at least about 10 V % to about 20 V %, based on the volume of theinitial feedstock; f. recovering middle distillate product from thefluidized catalytic cracking reaction and separation zone; and g.conveying at least a portion of remaining cycle oil from the fluidizedcatalytic cracking reaction and separation zone to the first and/orsecond hydrocracking reaction zone wherein the integrated process isoperated to afford flexibility based on a desired product slate byvarying the hydrocracking unit conversion efficiency in either or bothof the first and second hydrocracking zones, wherein varying thehydrocracking unit conversion efficiency is by one or more of; operatingwith reduced efficiency catalyst in the first or second hydrocrackingreaction zones to favor bottoms production and increase the quantity offeed to the fluidized catalytic cracking reactor thereby resulting in anincrease in its products olefins and/or gasoline; or operating with alevel of hydrogen feed that is relatively low to reduce the expense ofhydrogen and increase the quantity of feed to the to the fluidizedcatalytic cracking reactor thereby resulting in an increase in itsproducts olefins and/or gasoline.
 22. The process of claim 1, furthercomprising operating at least one flow meter to measure production atone of the outlets; and operating a controller in electroniccommunication with the flow meter programmed to instruct performance ofan adjustment based on the measured production.
 23. The process of claim22, wherein the measured production is the flow rate at the olefinoutlet.
 24. The process of claim 22, wherein the adjustment modifiesconversion efficiency in the first hydrocracking reaction zone or thesecond hydrocracking reaction zone.
 25. This process of claim 21,wherein step (g) comprises conveying a portion of the remaining cycleoil to the second hydrocracking reaction zone.
 26. This process of claim21, wherein step (g) comprises conveying a portion of the remainingcycle oil to the first hydrocracking reaction zone.
 27. This process ofclaim 21, further comprising discharging gases from the fluidizedcatalytic cracking reaction and separation zone.
 28. The process ofclaim 21, further comprising recovering naphtha from the fractionatingzone.
 29. The process of claim 21, further comprising recovering middledistillates from the fractionating zone.
 30. The process of claim 21,wherein a portion of the bottoms fraction from the fractionating zone isremoved from the process.
 31. The process of claim 21, wherein theportion that is removed is about 1 V % to about 10 V % of the bottomsfraction.
 32. The process of claim 21, wherein step (d) further includesintroducing an additional feedstock to fluidized catalytic crackingreaction and separation zone.
 33. The process of claim 21, wherein step(d) comprises conveying a fluidized cracking catalyst mixture includingthe fluidized cracking catalyst as a fluidized cracking base catalyst,and a catalyst additive.
 34. The process of claim 33, wherein thefluidized cracking base catalyst comprises about 60 wt % to about 95 wt% of the total fluidized cracking catalyst mixture.
 35. The process ofclaim 33, wherein the fluid cracking base catalyst is selected from thegroup consisting of clays and inorganic porous oxides.
 36. The processof claim 34, wherein the fluid cracking base catalyst has a bulk densityof 0.5 g/ml to 1.0 g/ml, an average particle diameter of 50 microns to90 microns, a surface area of 50 m²/g to 350 and a pore volume of 0.05ml/g to 0.5 ml/g.
 37. The process of claim 33, wherein the catalystadditive includes a shape-selective zeolite.
 38. The process of claim37, wherein the shape selective zeolite is characterized by an averagepore diameter that is less then the average pore diameter of Y-typezeolite.
 39. The process of claim 37, wherein the shape selectivezeolite is selected from the group consisting of ZSM-5 zeolite, zeoliteomega, SAPO-5 zeolite, SAPO-11 zeolite, SAPO-34 zeolite, pentasil-typealuminosilicate, and combinations comprising at least one of theforegoing shape selective zeolite.
 40. The process of claim 37, whereinthe shape selective zeolite having a bulk density of 0.5 g/ml to 1.0g/ml, an average particle diameter of 50 microns to 90 microns, asurface area of 10 m²/g to 200 m²/g and a pore volume of 0.01 ml/g to0.3 ml/g.
 41. The process of claim 37, wherein the fluid crackingcatalyst mixture includes about 5 wt % to about 40 wt % of the catalystadditive.
 42. The process of claim 37, wherein the catalyst additivecomprises about 20 wt % to about 70 wt % shape-selective zeolite. 43.The process of claim 37, wherein the catalyst additive comprises about30 wt % to about 60 wt % shape-selective zeolite.
 44. The process ofclaim 21, further comprising operating at least one flow meter tomeasure production at one of the outlets; and operating a controller inelectronic communication with the flow meter programmed to instructperformance of an adjustment based on the measured production.
 45. Theprocess of claim 44, wherein the measured production is the flow rate atthe olefin outlet.
 46. The process of claim 44, wherein the adjustmentmodifies conversion efficiency in the first hydrocracking reaction zoneor the second hydrocracking reaction zone.